Crocodile fern – is it a croc or is it not?

Ferns come in all shapes and sizes, and one of the nicest looking ferns available for houseplant growers is the Crocodile fern: Microsorum musifolium. A lot of people have problems with this fern, but if you have the right information, things will be a lot happier.

Of course the best advice on growing ferns is to pick a species that is right for the environment in which you live. But for us houseplant junglers, we like to have the tropical plants indoors – even if we live in cool climate Hobart.

Like the majority of ferns, Microsorum musifolium is a tropical plant. If you are in Hobart and you want to have one of these beauties in your home, the big thing you will need to do is to focus on replacing the missing climate aspects: warmth, humidity and water.

Avoid these conditions

Most ferns don’t like harsh afternoon sun, cold draughts and strong winds, so be sure to find a location indoors away from these aspects. The plant does need some light to grow and thrive, just not direct sun – remember it lives on the floor of the jungle or up a tree, protected from direct sun most of the year.

Warmth

This fern will enjoy a warm area, preferably between 17-25 degrees Celsius. It will be happier as an indoor plant to avoid cold drafts and sudden temperature changes. It can tolerate it a little colder but it won’t be terribly happy about it. Most people keep their homes heated to this temperature range, so if you are comfortable, your crocodile fern will be too. As they grow older, new fronds emerge from the rosette’s centre and unfold slowly. In the right conditions you can expect to have a range of leaf growth stages on your plant at any one time.

Humidity

For humidity, the Crocodile fern will enjoy the steamy environment of the bathroom – just keep it off the sunny window ledge. If you want it elsewhere, you can increase the local humidity by sitting the pot in a dish with a layer of gravel and water. Just be sure to keep the base of the pot just above the water level to avoid the potting mix getting too soggy.

Watering

The more light the plant has, the more water it will take up. If your fern isn’t getting a whole lot of light, it won’t be using a lot of water – so don’t water unless it needs it.

It may take you a little while to become accustomed to the water needs of your Crocodile fern. When you have potted it up, and given it a watering, allow it to drain thoroughly. Then, lift it up to feel how heavy it is. Every week, give it a lift, and notice if it feels a lot lighter. If it feels very light, it needs to be watered – and may be showing signs of thirst on its leaves. So give it a water, allow it to drain – then every other day, give it a lift and notice when it feels lighter. If the plant feels heavy then no water is needed. If you want to check on the moisture level in the pot, then grab your handy bamboo chopstick. Push it down the inside edge of the pot, all the way to the bottom. If the chopstick feels wet when you pull it out, don’t water. If the stick is dry – water it well and allow to drain before returning it its cover pot.

This observation of water needs will teach you a lot about your plant and its particular conditions in your home.

If you are a little late in watering the tips of the leaves may be crispy. Just take your little nail scissors, trim off the crispy bits, and give it a good watering.

Feeding

During their times of active growth, give the fern a liquid feed suitable for foliage plants – avoid pouring the water down the centre crown of the plant. Water it around the inside perimeter of the pot.

Ferns can be quite sensitive to fertilisers, so be sure to keep it half strength so you don’t overpower the plant. Remember, in the jungle, ferns grow at the edges of the stream or as epiphytes up a tree – there isn’t a lot of rich feeding happening in those locations.

Potting up and potting on

These plants are slow growers, don’t you won’t be repotting every year. Crocodile ferns are shallow rooted, so don’t plant it into a pot that’s going to have heaps of wet mix to go sour – just enough room in the pot to fit your finger between the root ball and the inside edge of the pot. You can also add a thin layer of gravel or LECA clay balls in the bottom of the pot to ensure good drainage.

What sort of potting mix?

Use a mix that is lighter, coarser, and more porous than you would for your regular houseplants. The Crocodile fern is epiphytic: meaning it can happily grow up the trunk of a hairy tree, like a tree fern (Dicksonia antarctica) and needs better drainage. A well-drained fern mix is good for them is as follows:

• One part moisture component: coconut coir – chop it up into smaller pieces if it looks to long.
• One and a half parts chunky things for drainage and aeration: perlite, vermiculite, pumice, lava rock, or a combination of these—but try not to use more than one part vermiculite.
• One part orchid bark: I prefer small size, 3-6mm
• Add 1 tablespoon of horticultural charcoal for each litre of the finished mix

Trouble Shooting

• Scorched foliage or pale leaves: Your plant is getting too much bright light. Crocodile ferns are understory plants, which means they grow under the jungle canopy where there is no direct light. Adjust the positioning of your fern to provide it with bright filtered light. 
• Yellowing leaves: If yellowing takes place once in a while , don’t be too alarmed. This is a natural part of plant life, for leaves to age and die. But if the yellowing is all over and is sudden, it indicates too much wet potting mix. Adjust your watering regime and check for moisture every time BEFORE you water. Microsorum Musifolium does like moisture, but not soggy, sour mix.
• Brown edges: Humidity is crucial for ferns and brown edges are a clear indicator of dry air. See the section above on humidity.
• Crispy leaves: Crispy leaves are a sign of underwatering, be sure that you are keeping the soil evenly moist, not soggy. Don’t allow the mix to dry out.
• Center of fern black and mushy: Crocodile Fern fronds tend to grow in a rosette formation from the centre of the plant. This creates an ideal location for water to pool and cause rot. When watering your fern make sure to water around the plant . Only water the potting mix, not the crown of the plant.
• Pests: Pest infestations are not a common issue for these ferns in nature, but in the home they can attract common pests such as scale and mealybug. Check between and under the leaves for bugs each time you water. Treat the pest straight away with your preferred bu killer.